This invention relates to a combination drilling, tapping and reaming machine, and more particularly to an improved such machine capable of operating at variable speeds and having improved characteristics which make it universally suitable for drilling, reaming, boring and tapping operations.
From the early days of industrialization, there existed the need for a machine to make holes in manufactured products, and as a result of such need an early invention produced what is universally known as a drill press. Typically when such press is in use, a workpiece is clamped onto the base of the associated machine beneath a powered drill bit, and subsequently the drilling operation is effected. For drilling multiple holes the parts on such early machines were repositioned relative to the associated drill bit each time a new hole in the part was to be made. To eliminate the need for repositioning the workpiece, there next was invented a device known as a radial drilling machine wherein the workpiece was fixed to the base, and the drill head itself was moved relative to the workpiece to form therein holes at a variety of different spots. Even so, the radial drilling machine had the disadvantage that it was extremely difficult to locate an associated drill bit to a pin-point drilling position.
As subsequent improvements, the industry developed a jig boring machine for more accurate control of movements in the X and Y direction, and even later in the Z axis direction for example by electromechanical apparatus, or more recently by programmable computer controlled devices (CNC). These latter machines, however, are extremely costly, and thus are not suitable for use by general industrial workshops of modest means.
Accordingly, it is an object of this invention to provide an improved drilling, tapping and reaming machine of the type in which the drilling head is easily repositionable relative to a stationary workpiece accurately to position the drilling head with minimum physical exertion by the operator, and at a very moderate cost compared to sophisticated electromechanical apparatus such as programmable computer controlled devices (CNC).
A further object of this invention to provide an improved machine of the type described in which has a drilling head that is movable manually relative to a stationary workpiece, and which includes manually operable means for releasably locking the drilling head in registry with predetermined points on the workpiece.
Still another object of this invention is to provide an improved, relatively small and yet sturdy machine of the type described which has thereon a drilling head which can be rapidly and accurately repositioned to multiple locations without exerting any significant force on the part of the operator or the associated equipment, and without compromising the accuracy (the perpendicularity) of the associated drilling, tapping or reaming operation.
Still a further object of this invention is to provide an improved, readily transportable machine of the type described, yet which unlike the machines in its class ideally counterreacts the opposite drilling force produced during a drilling operation, whereby the operator does not have to exert any additional force on the workpiece during the drilling operation.
Still a more specific object of this invention is to provide a machine of the type described having an improved electric motor and control means therefor which enable operation of the associated tool at variable speeds, and which automatically adjust the speed for maintaining a fixed torque on a workpiece, when an extra load is applied to the associated drill bit.
Other objects of this invention will be apparent hereinafter from the specification and from the recital of the appended claims, particularly when read in conjunction with the accompanying drawings.